In a single frequency cellular communications network with high system loads, coordinating radio resource allocation between neighboring cells improves the overall system capacity and coverage. In coordinated resource allocation, a set of radio resources in a cell are allocated to a User Equipment (UE) with the knowledge of allocation of the corresponding radio resources in neighboring cell(s). By properly coordinating the radio resource usage in the cells, inter-cell interference can be mitigated. For example, a UE that is experiencing interference from a neighboring cell may have better performance when the serving cell of that UE allocates radio resources to the UE over which the neighboring cell transmits at a low transmit power level.
Most of the current cellular communications networks utilize individual radio resource schedulers for each cell. Normally, there is limited or no coordination among the cells in the current single frequency cellular networks when the radio resources are assigned for downlink and uplink transmissions.
Starting with Release 8, the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) specifications include explicit support for Inter-Cell Interference Coordination (ICIC). In particular, a set of messages are defined that can be exchanged between enhanced, or evolved, Node Bs (eNBs) using the X2 interface. These messages provide information about the interference being created or experienced by the eNB issuing the messages. Using these messages, the inter-cell interference between neighboring cells may be taken into account by the individual cell schedulers of the different eNBs to at least partly mitigate the inter-cell interference.
While 3GPP LTE provides ICIC, the amount of information that can be exchanged over the X2 interface is limited in order to reduce backhaul bandwidth requirements. As such, the coordinated scheduling between cells is limited. Therefore, there is a need for systems and methods for improved coordinated scheduling between cells in a cellular communications network such as a 3GPP LTE network.